The variety of Malay brought to Sri Lanka from Indonesia beginning in the mid-seventeenth century was a largely isolating SVO language, whose grammar has changed radically over time. Modern Sri Lankan Malay (SLM) remains a language of predominantly Austronesian lexical inventory, but its grammar is now highly Dravidianised. This development is plausibly accounted for by postulating the convergence of L1 and L2 varieties in the many Muslim communities in which the interaction of Malay speakers and speakers of the Dravidian language Sonam (Sri Lankan Muslim Tamil) was intensive and the communal and cultural role of Sonam in the life of the Malay communities significant. This influence is noticeable from the diffusion of a number of Dravidian morphosyntactic features into SLM, including inter alia the accretion of a three-way morphological tense contrast where none was previously present, its suppression in negated clauses, and a robust finiteness contrast that marks the divergent status of matrix and non-matrix clauses. The SLM verb phrase, conservative in linear order, nevertheless strongly reflects a Sonam morphosyntactic model. A plausible catalyst for this development is accommodation of the discourse culture associated with the Sri Lankan sprachbund, in which the most recent event must appear last and must be realised as a matrix clause dominating one or more non-finite clauses. Those [non-matrix] clauses represent preceding events.